An inkjet recording method is a method of performing printing by jetting and attaching small liquid drops of ink to a recording medium such as paper, as well-known in the art. By this printing method, it is possible to print a high-resolution and high-quality image conveniently at a high speed with an inexpensive apparatus, and particularly in color printing, technology development has been recently conducted as an image forming method which may replace photographs.
When a color image is formed using an inkjet recording method, it is common to use at least a yellow ink, a magenta ink, a cyan ink and a black ink. In the related art, water-based ink is usually used as the inkjet ink in terms of safety such as malodor and hazard associated with fire-fighting. This ink is required to fall within suitable ranges in physical property values such as viscosity, surface tension and the like, to be excellent in storage stability and preventing clogging of a nozzle, to impart a recording image at a high concentration, and to be excellent in light fastness, ozone resistance, water resistance and moisture resistance.
Such a performance is mostly satisfied by using a water-based ink containing water or a mixture solution of water and a water-soluble organic solvent as a main solvent, but color tone, clearness, light fastness, ozone resistance, water resistance, moisture resistance and the like are influenced considerably by coloring agents, and various dyes have been studied in the related art.
In particular, in a color recording method using a plurality of color inks, uniform characteristics are required for all the constituting inks. Among them, a magenta dye has a problem in that discoloration by ozone or light (sunlight, fluorescent light and the like) or change in color tone occurs significantly, as compared to other dyes to cyan dye and a yellow dye). Accordingly, when ozone resistance or light fastness of the magenta ink is inferior to that of other inks, discoloration of the magenta ink causes the color tone of the whole image of printed matters to be changed, resulting in deteriorating the quality.
In the related art, an acidic dye having good chromogentic property and high water solubility, for example, C. I. Acid Red 52, 249 and 289 is known as a magenta dye for inkjet, but when such a dye is used alone, clogging of a nozzle hardly occurs due to the high water solubility, but the performances of the ozone resistance, light fastness and moisture resistance are very low.
Accordingly, Patent Document 1 discloses a magenta dye ink, which is excellent in light fastness, water resistance, color tone, clogging reliability and the like by using a magenta dye having a triazine side chain with a specific structure.
Further, Patent Document 2 discloses an inkjet recording liquid of a magenta color, which uses, as a colorant, a xanthene derivative substituted with an amino group which may have a substituent, and describes that due to excellent light fastness of the color image, color tone for good color reproducibility is excellent.